1. Field of the Invention
The present invention relates to structures for supporting semiconductor substrates during and following thinning thereof. More specifically, the present invention relates to support structures that are configured to entirely cover at least the outer peripheral portions of the active surfaces of semiconductor substrates to impart the semiconductor substrates with some rigidity following thinning thereof.
2. Background of Related Art
Since its inception, the trend in electronics has been to develop devices of ever-decreasing dimensions and ever-increasing capabilities. In order to drive these trends, semiconductor device manufacturers continually develop new technologies to put more processing power, more memory, and more ancillary functionality into the same or smaller amounts of space.
One of the approaches that has been taken for reducing the size of semiconductor device packages or for facilitating the incorporation of more semiconductor dice into packages of a standard size has been to reduce sizes of the various package features, including the wire bond heights, the thicknesses of adhesive layers, the thickness of packaging material that covers the package components, and the thicknesses of the semiconductor dice themselves.
The thicknesses of semiconductor dice may be reduced prior to singulation thereof from a semiconductor substrate, typically in the form of a silicon wafer, by reducing the thickness of the entire semiconductor substrate. This is typically done by so-called “backgrinding” processes, which include mechanical or chemical removal of material from the back side of the semiconductor substrate and, thus, from the devices, or dice, that have been fabricated on the opposite, active surface thereof.
State-of-the-art backgrinding processes are useful for reducing the thicknesses of 200 mm diameter silicon wafers, which are typically about 728 μm thick, and 300 mm diameter wafers, which are typically about 800 μm thick, to as thin as about 50 μm. When the thickness of a semiconductor substrate is reduced, however, the semiconductor substrate becomes less robust. For example, when the thickness of a 200 mm diameter silicon wafer is reduced to about 230 μm or less, it becomes pliable and is prone to sagging when positioned on an edge or when an edge thereof is handled. As a consequence of the reduced robustness of thinned semiconductor substrates, the semiconductor devices that have been fabricated thereon are more likely to be damaged when thinned semiconductor substrates are handled or packaged.
Moreover, when semiconductor substrates are thinned, they are typically secured, in active surface-down orientation, to a carrier, such as a vacuum chuck. While the semiconductor substrate may be adequately secured to the carrier, the active surface of the semiconductor substrate may not be completely sealed from chemical backgrinding/polishing agents or particles of removed material. Thus, material may be removed from the active surface of the semiconductor substrate or the active surface may become undesirably contaminated.
Accordingly, there are needs for structures and methods for supporting semiconductor substrates and for sealing the active surfaces thereof during and following thinning thereof.